Problem with "if" and "fi".....

[Heron Ordoņez]

I am having this problem...
when exporting from LyX to Postscript and print (my print comand is gv, so i
can view the results before actually printing) i have noticed that the "if"
the "fi" and the "ff" dont show in the output, the space is left blank but
the chars are gone. However, "Fi" "If" and "Ff" do show...
what can it be? prob in my config?
i am using teTeX under Slackware
if u whant to see the lyx file and the ps output i can send them
thanks